<p>Learn about Rh incompatibility and Rh disease during pregnancy, including prevention of Rh disease and what to expect during pregnancy.</p>

<p>Rhesus (Rh) factor is a group of proteins that occurs on the surface of some people's red blood cells. If you have Rh factor on your red blood cells, you are referred to as Rh-positive. If you do not have Rh factor, you are Rh-negative. Rh incompatibility is when an Rh-negative mother becomes pregnant with an Rh-positive baby. If the unborn baby’s Rh-positive red blood cells cross the placenta and reach the mother, her immune system will produce antibodies that will destroy the baby’s red blood cells. This is the cause of a complication called Rh hemolytic disease in the unborn baby. </p>

<h2>Key points</h2>
<ul><li>Rh incompatibility is when an Rh-negative mother becomes pregnant with an Rh-positive baby, which can cause Rh hemolytic disease.</li>
<li>Women who are Rh-negative are given an injection of Rh immunoglobulin during and after pregnancy to block the immune system from harming the unborn baby.</li>
<li>If the unborn baby shows signs of Rh hemolytic disease, early labour may need to be induced, so that the mother’s antibodies do not destroy too many of the baby’s red blood cells.</li></ul>

<p>Learn about Rh incompatibility and Rh disease during pregnancy, including prevention of Rh disease and what to expect during pregnancy.</p>

<p>Rhesus (Rh) factor is a group of proteins that occurs on the surface of some people's red blood cells. If you have Rh factor on your red blood cells, you are referred to as Rh-positive. If you do not have Rh factor, you are Rh-negative. Rh incompatibility is when an Rh-negative mother becomes pregnant with an Rh-positive baby. If the unborn baby’s Rh-positive red blood cells cross the placenta and reach the mother, her immune system will produce antibodies that will destroy the baby’s red blood cells. This is the cause of a complication called Rh hemolytic disease in the unborn baby. </p>

<h2>Key points</h2>
<ul><li>Rh incompatibility is when an Rh-negative mother becomes pregnant with an Rh-positive baby, which can cause Rh hemolytic disease.</li>
<li>Women who are Rh-negative are given an injection of Rh immunoglobulin during and after pregnancy to block the immune system from harming the unborn baby.</li>
<li>If the unborn baby shows signs of Rh hemolytic disease, early labour may need to be induced, so that the mother’s antibodies do not destroy too many of the baby’s red blood cells.</li></ul>

<p>A baby with Rh hemolytic disease may be born with jaundice or anemia. The most severe symptom, which can be diagnosed by ultrasound during pregnancy, is the accumulation of fluid, called hydrops, in the baby’s body.</p><h2>Preventing Rh incompatibility</h2><p>Early in pregnancy, blood tests are done to determine the woman’s blood type and Rh factor. Women who are found to be Rh-negative are given an injection of Rh immunoglobulin, also called Rhogam, during and after pregnancy. This is an antibody that blocks the woman’s immune system from producing the antibodies that destroy the unborn baby’s red blood cells. Women who are Rh-negative should be given the injection in all their pregnancies. Rh immunoglobulin is given at 28 weeks of pregnancy, and again within 72 hours of childbirth. The injection is given after an amniocentesis, after any episodes of vaginal bleeding, and at any time where the placenta could be disturbed, such as after a blow to the stomach. Rh immunoglobulin is also given to Rh-negative women after any miscarriage.</p>
<figure class="asset-c-80"><span class="asset-image-title">Rh factor inheritance: Example 1</span>
<img src="https://assets.aboutkidshealth.ca/akhassets/Rh_inheritance_1_MED_ILL_EN.jpg" alt="Chart of chromosomal distribution from an Rh-positive father, with two Rh-positive chromosomes, and an Rh-negative mother" />
<figcaption class="asset-image-caption">In this example, the father is Rh-positive and the mother is Rh-negative. All the children of this couple will inherit the dominant Rh+ allele from their father and will be Rh-positive. The mother should be given Rh immunoglobulin injections during all her pregnancies.</figcaption>
</figure>
<figure class="asset-c-80">
<span class="asset-image-title">Rh factor inheritance: Example 2</span>
<img src="https://assets.aboutkidshealth.ca/akhassets/Rh_inheritance_2_MED_ILL_EN.jpg" alt="Chart of chromosomal distribution from a father with one Rh-positive chromosome and one Rh-negative and an Rh-negative mother" />
<figcaption class="asset-image-caption">In this example, the father is Rh-positive and the mother is Rh-negative. The children of this couple may be either Rh-positive or Rh-negative, depending on which gene copy they inherit from their father. The mother should be given Rh immunoglobulin during pregnancy as a precaution.</figcaption>
</figure>
<h2>What to expect throughout pregnancy</h2><p>If the pregnant mother is Rh-negative, the mother’s blood will be tested for antibodies throughout the pregnancy. If there are Rh antibodies in the mother’s blood, the father of the baby should also be tested for Rh factor. If they are Rh-negative, the baby will be Rh-negative, and therefore is not at risk for Rh hemolytic disease. If the father is Rh-positive, the pregnant mother will be offered an amniocentesis to determine whether the unborn baby is Rh-negative or Rh-positive. If the baby is Rh-positive, the baby’s health will be monitored using ultrasound, and amniocentesis or another test called cordocentesis may be done throughout the pregnancy to determine if the unborn baby is developing Rh hemolytic disease. The tests need to be done every two to four weeks, and pose a small risk of miscarriage.</p><p>If the unborn baby shows signs of Rh hemolytic disease, early labour may need to be induced, so that the mother’s antibodies do not destroy too many of the baby’s red blood cells. If Rh hemolytic disease is severe and labour cannot be induced yet, it is possible to give the baby blood transfusions while they are still in the womb. Through proper treatment, it is possible to save the lives of up to 90% of babies who have Rh hemolytic disease.</p>

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